The Oracle’s Library explores the origins behind April Fool’s Day. Back before the Gregorian Calendar was established, people in the middle ages celebrated the New Year following the return of the vernal equinox around the 21st of March. From as early as the 4th Century BCE up to the medieval era, societies across Europe reserved March 25th for the New Year’s celebration named the Feast of Annunciation.

The Annunciation and Equinox

The Feast of Annunciation—also known as Lady Day—was one of the only two celebrations permitted by the Roman Catholic Church to be held during Lent just before Easter. In some places in England, no work was to be done in observance of this holiday. The feast celebrates the day the angel Gabriel visited Mary to mark the day of Incarnation of the Second Person into the Holy Trinity. The angel said, “Ave, gratia pena, Dominus tecum” or “Hail, full of grace, the Lord is with thee”(Luke 1:28). This salutation has been shaped into the words of the common “Hail Mary” prayer with her response, “fiat mihi secundum verbum tuum” or “Let it be done to me according to thy word”.

The New Year of the Gregorian Calendar

In 1582, when the Gregorian Calendar replaced the old Julian Calendar of Caesar under Pope Gregory XIII, the earliest New Year’s celebrations held on Lady Day were also shifted to the new calendar start date on January 1st. The implementation of the Gregorian Calendar also immediately changed the date by 10 whole days from October 5th to October 15th to make up for the discrepancies between the calendar seasons and the vernal equinox. This discrepancy is a natural phenomenon caused by the precession of the equinox (precession occurs at a rate of about 1 degree every 70 years).

In one day, the New Year’s celebration was hacked and switched to January 1st in the Roman Catholic world. The Eastern Orthodox tradition did what many of the people living across Europe did in response—nothing. They continued to hold a feast just after the vernal equinox on March 21st to celebrate the Annunciation and the return of the New Year. Hence, March 21st became the day of fools, when those who were uniformed by the Pope were still celebrating Lady Day. After the Julian Calendar was replaced, March 21st became April 1st and Voilà! We have April Fool’s Day.

Quarters of the Seasons and Lady Day

In history and across various civilizations, festivities are often held near each quarter of the seasons. The significance of Lady Day to the early Europeans was not only about a ritual practice, but also about civil contracts in agrarian society. An echo of this old practice remains in the end of the UK fiscal tax year. Other celebrations that fall during this season are the celebration of Holi in India—with colorful powders and mischievous pranks. To read more on the shifting calendars, check out The History of the New Year.

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photo credit: Will Humes via photopin cc